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SX8723E083TRT View Datasheet(PDF) - Semtech Corporation

Part Name
Description
MFG CO.
SX8723E083TRT
Semtech
Semtech Corporation Semtech
'SX8723E083TRT' PDF : 53 Pages View PDF
SX8723
ZoomingADC™ for Pressure and Temperature Sensing
ADVANCED COMMUNICATIONS & SENSING
ZoomingADC
Features
The ZoomingADC is a complete and versatile low-power analog front-end interface typically intended for sensing
applications.
In the following text the ZoomingADC will be referred as ZADC.
The key features of the ZADC are:
Programmable 6 to 16-bit dynamic range over-sampled ADC
Flexible gain programming between 0.5 and 1000
Flexible and large range offset compensation
3-channel differential or 5-channel single-ended input
2-channel differential reference inputs
Power saving modes
Overview
Analog
Inputs
VSS
VREF
AC2
AC3
AC4
AC5
AC0
fs
AC1
VIN
PGA1
GD1
PGA2
VD1
GD2
PGA3
+ VD2
-
GD3
fs
+
VIN,ADC
-
16
ADC
OFF2
OFF3
Input
Selection
VBATT +
Reference VSS
-
Inputs VREF +
VSS
-
VREF,ADC
Gain 1
Gain 2 Offset 2
Gain 3 Offset 3
Reference
Selection
ZOOM
Figure 8 - ZADC General Functional Block Diagram
The total acquisition chain consists of an input multiplexer, 3 programmable gain amplifier stages and an over
sampled A/D converter. The reference voltage can be selected on two different channels. Two offset compensation
amplifiers allow for a wide offset compensation range. The programmable gain and offset allow the application to
zoom in on a small portion of the reference voltage defined input range.
ZADC Description
Acquisition Chain
Figure 8 shows the general block diagram of the acquisition chain (AC). A control block (not shown in Figure 8)
manages all communications with the I2C peripheral. The clocking is derived from the internal 4 MHz Oscillator.
Analog inputs can be selected through a 6 input multiplexer, while reference input is selected between two differential
channels. It should however be noted that only 5 acquisition channels (including the VREF) are available when
configured as single ended since the input amplifier is always operating in differential mode with both positive and
negative input selected through the multiplexer.
The core of the zooming section is made of three differential programmable amplifiers (PGA). After selection of an
input and reference signals VIN and VREF,ADC combination, the input voltage is modulated and amplified through
stages 1 to 3. Fine gain programming up to 1'000 V/V is possible. In addition, the last two stages provide
programmable offset. Each amplifier can be bypassed if needed.
V1.5 © 2007 Semtech Corp.
15
www.semtech.com
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